Fixed wrong current directory while creating a new Bookmark

[ganlub]

The first time I added a Bookmark (<a>) everything went well. But the following I added took the directory of the "visually selected one" instead of its own.

[ganlub]

On :help ctrlspace section 5.5, it says to press <a> to add a new Bookmark but on the Key Reference there's <a> and <A> to "Add a new bookmark (A - with CWD)". Using <A> works good, but if I use <a>, it happens what I posted on my previous comment.

[jyscao]

@Konfekt do you know if this PR is still relevant (it dates back to 2016...)?

[Konfekt]

Yes, It is. Indeed a proposed to add the selected bookmarked directory which is pointless.

[Konfekt]

@jyscao : This looks good to go as I see little benefit in adding the selected already added bookmark.

@ganlub : Would you mind syncing to master to resolve conflicts?